1. Field
Embodiments of the present invention generally relate to equipment for performing semiconductor device fabrication, and more particularly, to an electrostatic chuck for supporting a semiconductor wafer during processing.
2. Description of the Related Art
Electrostatic chucks are widely used for providing support to substrates (also referred to herein as semiconductor wafers or wafers) within semiconductor processing equipment such as a plasma processing chamber. An electrostatic chuck generally holds a substrate in a stationary position during processing of the substrate, i.e., during material deposition or etching. Electrostatic chucks utilize capacitive and Johnsen-Rahbeck attractive forces for holding the substrate in position.
One type of electrostatic chuck includes a body and a fluid distribution element covered with a layer of a dielectric material thereby forming a support surface. The body is generally conductive such that the body forms an electrode of the electrostatic chuck. A substrate is placed onto the support surface. The fluid distribution element includes a plenum that carries the fluid through multiple passages formed in the support surface of the electrostatic chuck for distributing a heat transfer fluid such as a gas between the support surface of the chuck and the backside of the substrate. Generally, the gas fills the interstitial area between the electrostatic chuck and the substrate, thus enhancing the rate and uniformity of heat transfer between electrostatic chuck and the substrate.
In plasma processing chambers, the electrostatic chuck is subjected to high power radio frequency (RF) fields and high density plasmas in the vicinity of the substrate. In such plasma processing chambers, it is possible to have the gas breakdown due to high electric field generation in the gas passages. The operation and service life of the electrostatic chuck is adversely affected by plasma formation in the gas passages. Such plasma may damage the substrate, the electrostatic chuck or both. Furthermore, plasma formation in a gas passage can lead to arcing that forms particulate contaminants in the chamber.
Some conventional electrostatic chucks (ESC) have arcing problems around backside gas holes and lift pin holes. The base of the ESC, which is bare aluminum, is located just below a top ceramic layer and is too close to the ESC surface as a result of how the backside gas holes are made. If a wafer is not centered correctly on the ESC or if the chucking power is lost, then all RF Power (Plasma) passes through the lowest resistance point, which is the bare aluminum, and creates a lot of arcing.
In addition, when the lift pins move up and down, they rub against the lift pin hole areas, which are made of aluminum, which causes formation of aluminum particles. These aluminum particles act as an RF antenna and attract the RF Power and hence also cause arcing.
Accordingly, there is need in the art for an improved electrostatic chuck.